1. Field of the Invention
The present invention is broadly concerned with compositions and methods for sorbing and/or destroying dangerous substances such as chemical and biological warfare agents. The methods of the invention are carried out by simply contacting the target substance with particulate metal oxide compositions. These compositions can be unmodified, or alternately, the particulate metal oxides can be coated with a second metal oxide, have reactive atoms or mixtures of reactive atoms stabilized on their surfaces, or have species adsorbed on their surfaces. In another embodiment, the particulate metal oxides (unmodified or modified) can be pressed to form pellets which possess the same destructive abilities as the metal oxides in powder form. Methods in accordance with the invention require the use of minimal liquids, thus resulting in very little effluent. Furthermore, the particulate metal oxide compositions utilized in the methods of the invention are not harmful to equipment or to humans and can easily be used directly at the site of contamination.
2. Description of the Prior Art
The threat of biological and chemical warfare has grown considerably in recent times. Numerous countries are capable of developing deadly biological and chemical weapons. Some potent biological agents include the following: bacteria such as Bacillus anthracis (anthrax) and Yersinia pestis (plague); viruses such as variola virus (small pox) and flaviviruses (hemmorhagic fevers); and toxins such as botulinum toxins and saxitoxin. Some potent chemical agents include: blister or vesicant agents such as mustard agents; nerve agents such as methylphosphonothioc acid (VX); lung damaging or choking agents such as phosgene (CG); cyanogen agents such as hydrogen cyanide; incapacitants such as 3-quinuclidinyl benzilate; riot control agents such as CS (orthochlorobenzylidene malononitrile); smokes such as zinc chloride smokes; and some herbicides such as 2,4-D (2-4-dichlorophenoxyacetic acid).
All of the above agents, as well as numerous other biological and chemical agents, pose a significant risk to private citizens as well as to military personnel. For example, vesicant agents burn and blister the skin or any other part of the body they contact, including eyes, mucus membranes, lungs, and skin. Nerve agents are particularly toxic and are generally colorless, odorless, and readily absorbable through the lungs, eyes, skin, and intestinal track. Even a brief exposure can be fatal and death can occur in as quickly as 1 to 10 minutes. Biological agents such as anthrax are easily disseminated as aerosols and thus have the ability to inflict a large number of casualties over a wide area with minimal logistical requirements. Many biological agents are highly stable and thus can persist for long periods of time in soil or food.
There are currently two general types of decontamination methods for biological agents: chemical disinfection and physical decontamination. Chemical disinfectants, such as hypochlorite solutions, are useful but are corrosive to most metals and fabrics, as well as to human skin. Physical decontamination, on the other hand, usually involves dry heat up to 160.degree. C. for 2 hours, or steam or super-heated steam for about 20 minutes. Sometimes UV light can be used effectively, but it is difficult to develop and standardize for practical use.
These methods have many drawbacks. The use of chemical disinfectants can be harmful to personnel and equipment due to the corrosiveness and toxicity of the disinfectants. Furthermore, chemical disinfectants result in large quantities of effluent which must be disposed of in an environmentally sound manner. Physical decontamination methods are lacking because they require large expenditures of energy. Both chemical and physical methods are difficult to use directly at the contaminated site due to bulky equipment and/or large quantities of liquids which must be transported to the site. Finally, while a particular decontamination or disinfection method may be suitable for biological decontamination, it is generally not effective against chemical agents. There is a need for decontamination compounds which are effective against a wide variety of both chemical and biological agents, have low energy requirements, are easily transportable, do not harm skin or equipment, and employ small amounts of liquids with minimal or no effluent.